LRO LOLA Gridded Data Record Geoid (GDRDGM)

GDRDGM – Gridded Data Record Geoid

Instrument: Lunar Orbiter Laser Altimeter

PDS Data Set ID: LRO-L-LOLA-4-GDR-V1.0

For more information about LOLA RDR and derived products, see the RDR Product SIS.

For more information about all LOLA products, see the LOLA Archive Volume SIS.

The Lunar Orbiter Laser Altimeter (LOLA) Gridded Data Record Geoid (GDRDGM) data product is a map of the lunar geoid heights. The geoid is defined as the equipotential surface whose mean equatorial radius is 1736. The map resolution is 4 pix/deg by 4 pix/deg. The gravity field model is truncated at degree 60.

The .IMG maps are in the form of a binary table with one row for each 0.25 degrees of latitude, pixel registered. Because the geoid height was calculated from the gravity field truncated at degree 60, this is sufficient to capture the long-wavelength features of the geoid height changes. Map values are relative to a radius of 1737.4 km. The geoid height map can be used to derive topography from the other LOLA elevation (or planetary radius) maps. This is done by subtracting the geoid height from the LOLA elevation. The use of topography instead of elevation can be important, e.g. for studies which need to determine downslope direction of flow.

The geoid is scaled and offset.

Geoid = DN * SCALING_FACTOR + OFFSET. (DN = Digital Number)

LOLA GDRDGM products have the following file names:



mmmmmm = input geoid model (GLGM-3, LP150Q, or SGM100I)

xxx = file type/extension

.IMG = image file

.LBL = detached PDS label

.JP2 = JPEG2000 file

_JP2.LBL = detached PDS label

In ODE, GDRDGM products have the following product IDs: